Comparison and Storage Stability of Biodiesels from Expired oils

Abstract

Transesterification of expired vegetable oils is possible by heating them with a significant amount of methanol and an acidic or basic catalyst to improve the reaction rate and yield. In this study 4 samples have been selected, including 4 types of vegetable oils, namely: soybean, sunflower, rapeseed, pumpkin seed. The operative conditions of the reaction were reaction time (4 h), catalyst concentration (1 w/wt %), and oil-to-methanol molar ratio (6:1). The parameters studied to compare the quality of biodiesel obtained by each type of compound are: yield, pH, density, acid value. The results shows that The pumpkin seed have a positive effect on increasing the yield of Soybean biodiesels as well as biodiesel blends based on Soybean, Sunflower and rapeseed. This paper examines also the degradation of several biofuels in comparison with fossil fuels (Diesel and gasoline) with different storage conditions over 9 Weeks period. The Results indicated that: High temperature combined with the lighting strongly enhances the degradation phenomenon. The acid value of biodiesel (HM) is rapidly increasing at a rate of 0.91 mg KOH/g /Week. The pH of diesel has experienced a strong decrease of 66%. In comparison with Diesel, Diesel degrades strongly and rapidly from a biodiesel in terms of Acid Value, pH and Density.